More Dart — Literally

A collection of extensively tested extensions that make Dart a better place:

Library	Description
async	Extensions to Stream.
cache	Caching strategies and their expiry policy.
char_matcher	Character classes, their composition, and operations on strings.
collection	Extensions to Iterable and new collection types.
comparator	Common comparators, and extensions to perform advanced operations.
diff	Tools for comparing lists.
feature	Information about the runtime environment.
functional	Types and features known from functional programming.
graph	Graph-theory objects and algorithms.
interval	Continuous interval data type over a practical range.
math	Common mathematical functions.
number	Number types: fraction, complex, quaternion.
printer	Fluent interface to configure sophisticated formatters.
temporal	Extensions to DateTime and Duration types.
tuple	Tuple extension methods on generic records.

And there are more to come ...

Highlights

Collections & Iterables

Powerful extensions and specialized data structures that complement dart:collection:

import 'package:more/collection.dart';

// Integer ranges with custom stepping
0.to(10, step: 2); // [0, 2, 4, 6, 8]

// Sliding windows and fixed chunks
[1, 2, 3, 4, 5].window(3); // [[1, 2, 3], [2, 3, 4], [3, 4, 5]]
[1, 2, 3, 4, 5].chunked(2); // [[1, 2], [3, 4], [5]]

// Combinatorics: combinations, permutations, and power sets
['a', 'b', 'c'].combinations(2); // [['a', 'b'], ['a', 'c'], ['b', 'c']]

// Rich collections: Multimaps, BiMaps, BitLists, and Sorted/Ordered lists
final multimap = ListMultimap<String, int>()
  ..add('even', 2)
  ..add('even', 4)
  ..add('odd', 1);
print(multimap['even']); // [2, 4]

Graph Theory & Algorithms

Flexible graph data structures with built-in pathfinding, search, and topological analysis:

import 'package:more/graph.dart';

// Create a directed weighted graph
final graph = Graph<String, num>.directed()
  ..addEdge('A', 'B', value: 4)
  ..addEdge('A', 'C', value: 2)
  ..addEdge('C', 'B', value: 1);

// Find shortest path using Dijkstra's algorithm
final path = graph.shortestPath('A', 'B');
print(path?.vertices); // ['A', 'C', 'B']
print(path?.cost); // 3

// Topological sort and cycle detection
final sorted = graph.topological('A');
final hasCycle = graph.hasCycle();

Numbers & Mathematics

Exact rational arithmetic, complex numbers, and extended math functions on integers:

import 'package:more/math.dart';
import 'package:more/number.dart';

// Exact rational arithmetic
final a = Fraction(1, 3);
final b = Fraction(1, 6);
print(a + b); // Fraction(1, 2)
print(Fraction.tryParse('3/4')); // Fraction(3, 4)

// Complex numbers & quaternions
final c = Complex(3, 4);
print(c.abs()); // 5.0

// Math extensions on int and BigInt
12.gcd(8); // 4
5.factorial(); // 120
17.isProbablyPrime; // true
123.digits(); // [3, 2, 1]

Composable Printers

A fluent, composable model to format strings, numbers, and dates without complex templates:

import 'package:more/printer.dart';

// Formatted numbers with padding, prefix, and precision
final currency = FixedNumberPrinter(precision: 2).before(r'$').padLeft(8);
print(currency(12.5)); // '  $12.50'

// Human-readable binary/decimal quantities
final human = HumanNumberPrinter.binary();
print(human(1024 * 1024 * 3)); // '3 Mi'

// Configurable date and time formatting
final date = DateTimePrinter.date();
print(date(DateTime(2025, 1, 15))); // '2025-01-15'

Temporal & Intervals

Fluent manipulation of dates, durations, and continuous intervals:

import 'package:more/interval.dart';
import 'package:more/temporal.dart';

// Truncate dates to specific units
final now = DateTime(2025, 5, 12, 14, 23, 45);
print(now.truncateTo(TimeUnit.hour)); // 2025-05-12 14:00:00.000

// Continuous interval operations
final intA = Interval(1, 5); // [1..5]
final intB = Interval(3, 7); // [3..7]
print(intA.intersection(intB)); // [3..5]

Unicode & Character Matching

Full Unicode 18.0.0 compliance featuring standard normalization algorithms and composable character classifiers:

import 'package:more/char_matcher.dart';
import 'package:more/collection.dart';

// Unicode Normalization (NFC, NFD, NFKC, NFKD)
'e\u0301le\u0300ve'.normalize(); // 'élève'
'①'.normalize(form: NormalizationForm.nfkc); // '1'
'ffi'.normalize(form: NormalizationForm.nfkc); // 'ffi'

// Match official Unicode categories, scripts, and properties
final greek = UnicodeCharMatcher.scriptGreek();
final whitespace = UnicodeCharMatcher.whiteSpace();

// Filter, collapse, and clean strings beyond basic ASCII
greek.retainFrom('Hello Ελληνικά!'); // 'Ελληνικά'
whitespace.collapseFrom('lots   of   spaces', ' '); // 'lots of spaces'

// Compose matchers with set operations
final latinOrDigits = UnicodeCharMatcher.scriptLatin() | CharMatcher.digit();
latinOrDigits.retainFrom('Hello 123! π'); // 'Hello123'

// Unicode-aware string splitting preserving surrogate pairs
'Dart 🎯'.toList(unicode: true); // ['D', 'a', 'r', 't', ' ', '🎯']

Caching Strategies

Self-loading asynchronous caches with LRU, FIFO, and duration-based expiry policies:

import 'package:more/cache.dart';

// Self-loading LRU cache with maximum size
final cache = Cache<String, int>.lru(
  loader: (key) => expensiveCalculation(key),
  maximumSize: 100,
);
final value = await cache.get('hello');

Misc

This library is open source, stable and well tested. Development happens on GitHub. Feel free to report issues or create a pull-request there. General questions are best asked on StackOverflow.

The package is hosted on dart packages. Up-to-date class documentation is created with every release.

Contributing

The goal of the library is to provide a loose collection of carefully curated utilities that are not provided by the Dart standard library. All features must be well tested. New features must have significant advantages over alternatives, such as code reduction, readability improvement, speed increase, memory reduction, or improved accuracy. In case of doubt, consider filing a feature request before filing a pull request.

History

This library started in April 2013 as I was working through the puzzles of Project Euler and encountered some missing features in Dart. Over time the code grew and became more useful in many other places, so I created this reusable library.

Some parts of this library are inspired by similar APIs in Google Guava (Google core libraries for Java) and Apache Commons (a repository of reusable Java components).

License

The MIT License, see LICENSE.